Bore Guide #4 Browning A-Bolt, Remington, Ruger, Springfield, Winchester, Savage Bolt Action Bore Guides are 100% solvent resistant. Bore Guide is machined with a snout that extends into rifle chamber. Silicone "O" ring that seals off chamber. Aligns the cleaning rod with center of rifle bore. Insures no damage can be done by a jag or a brush while cleaning.